The present invention relates to epoxy compounds and epoxy resin compositions containing said epoxy compounds as an essential ingredient.
Cured epoxy resins are widely used as electrical insulating materials, adhesives and coating compositions because of improved electrical properties, adhesiveness, and heat resistance. Further improvement in heat resistance, mechanical properties and electrical properties is desired for epoxy resins as severer requirements are imposed in their advanced applications, particularly electric and electronic applications.
Epoxy resins known to form a cured product having higher heat resistance are illustrated as, for example, ortho-cresol novolak epoxy resins (EOCN) and phenolic novolak epoxy resins. However, there still remains a problem that the cured products of these epoxy resins, are brittle.
In addition to the fact that cured epoxy resins are brittle or less flexible, an attempt to improve their heat resistance often results in a further decrease in flexibility. Lack of flexibility gives rise to many problems. For example, a coating composition forms a coating which is susceptible to cracking upon the application of an impact, an adhesive fails to achieve a desired level of peel strength, and a casting composition results in castings which are susceptible to cracking under thermal shock.
Known epoxy resins having improved flexibility are polyalkylene glycol diglycidyl ethers, lactone-modified epoxy resins and the like. Despite improved flexibility, cured articles of these resins are decreased in other properties including heat resistance and mechanical strength. There is a need for epoxy resins having a sufficient degree of heat resistance and flexibility to meet their advanced applications.
In the field of laminated boards, those having a low dielectric constant are desired for the purpose of increasing the compilation speed of computers. Since currently available techniques of fine patterning and densifying to increase the compilation speed have almost reached a physical limit, attention is now paid to another approach to reduce the dielectric constant of board material. Polyethylene and fluoride resins have been proposed as materials having a low dielectric constant. Most of these resins have drawbacks including low mechanical strength, poor dimensional stability, and low copper foil peel strength.
It has also been considered to substitute quartz for glass substrate. An undesirable problem which accompanies the substitution is that a drill used to perforate the substrate becomes severely worn.
There is a requisite for an epoxy resin which is reduced in dielectric constant while maintaining the inherent properties of epoxy resins.